tequilaOS/platform_frameworks_native
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Fix addition/overflow checks.

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For unsigned arithmetic, use:

(a + b < a) to detect whether a+b wraps
(a > c / b) to detect whether a*b > c

Bug: 120078455
Test: builds and boots
Change-Id: Ic4f4d44f7c0656caa115f90f4cfa130192914949
(cherry picked from commit da2f2fd0f4)
This commit is contained in:
Martijn Coenen 2020-01-22 10:46:25 +01:00
parent 876a1960e4
commit 93fe51840e
2 changed files with 10 additions and 3 deletions
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3
libs/binder/BufferedTextOutput.cpp
View file

@ -49,9 +49,10 @@ struct BufferedTextOutput::BufferState : public RefBase
}
status_t append(const char* txt, size_t len) {
if (len > SIZE_MAX - bufferPos) return NO_MEMORY; // overflow
if ((len+bufferPos) > bufferSize) {
if ((len + bufferPos) > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((len+bufferPos)*3)/2;
if (newSize < (len+bufferPos)) return NO_MEMORY; // overflow
void* b = realloc(buffer, newSize);
if (!b) return NO_MEMORY;
buffer = (char*)b;

10
libs/binder/Parcel.cpp
View file

@ -520,8 +520,10 @@ status_t Parcel::appendFrom(const Parcel *parcel, size_t offset, size_t len)
const sp<ProcessState> proc(ProcessState::self());
// grow objects
if (mObjectsCapacity < mObjectsSize + numObjects) {
if ((size_t) numObjects > SIZE_MAX - mObjectsSize) return NO_MEMORY; // overflow
if (mObjectsSize + numObjects > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((mObjectsSize + numObjects)*3)/2;
if (newSize*sizeof(binder_size_t) < mObjectsSize) return NO_MEMORY; // overflow
if (newSize > SIZE_MAX / sizeof(binder_size_t)) return NO_MEMORY; // overflow
binder_size_t *objects =
(binder_size_t*)realloc(mObjects, newSize*sizeof(binder_size_t));
if (objects == (binder_size_t*)nullptr) {
@ -1399,8 +1401,10 @@ restart_write:
if (err != NO_ERROR) return err;
}
if (!enoughObjects) {
if (mObjectsSize > SIZE_MAX - 2) return NO_MEMORY; // overflow
if ((mObjectsSize + 2) > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((mObjectsSize+2)*3)/2;
if (newSize*sizeof(binder_size_t) < mObjectsSize) return NO_MEMORY; // overflow
if (newSize > SIZE_MAX / sizeof(binder_size_t)) return NO_MEMORY; // overflow
binder_size_t* objects = (binder_size_t*)realloc(mObjects, newSize*sizeof(binder_size_t));
if (objects == nullptr) return NO_MEMORY;
mObjects = objects;
@ -2685,6 +2689,8 @@ status_t Parcel::growData(size_t len)
return BAD_VALUE;
}
if (len > SIZE_MAX - mDataSize) return NO_MEMORY; // overflow
if (mDataSize + len > SIZE_MAX / 3) return NO_MEMORY; // overflow
size_t newSize = ((mDataSize+len)*3)/2;
return (newSize <= mDataSize)
? (status_t) NO_MEMORY